A county corporate or corporate county was a type of subnational division used for the administration of justice in certain towns and cities in England, Wales, and Ireland. They arose when the monarch gave a borough corporation the right to appoint its own sheriffs, separating that borough from the jurisdiction of the sheriff of the county in which it lay.

They were legally described as forming separate counties, but in both contemporary usage whilst they existed and in discussion by modern historians the counties corporate are generally distinguished from the wider counties. From Tudor times onwards lord lieutenants were appointed to oversee the militia for each county; with the exceptions of London and Haverfordwest, each county corporate was covered by the lieutenant of an adjoining county. Provisions were also made allowing court cases arising from counties corporate to be heard at the assizes for the adjoining county.

"County corporate" was not a statutory name, but was a commonly used description for such towns and cities. Other terms used included county of itself or city and county. They were similar to an independent city or consolidated city-county in other countries. The equivalent term in Scotland was a county of a city.

In England and Wales, county boroughs were created from 1889 onwards, which were similar in that they were places that were independent from their surrounding counties for local government functions. There was some overlap between the places that were counties corporate for judicial purposes and the places that were county boroughs for local government purposes. Sheriffs retained some judicial functions until 1972 when the courts system was reformed. The counties corporate were abolished in England and Wales in 1974, although some of the former counties corporate still retain the right to appoint a ceremonial sheriff.

Counties were originally areas used for the administration of justice. Each had a sheriff, who was usually appointed by the monarch. Separately, boroughs were certain towns or cities which had a degree of self-government. The rights and functions belonging to each borough varied, depending on what had been included in the borough's charter. The inhabitants of a borough were deemed in law to be capable of acting as a single corporate person, allowing the borough to enter into contracts and litigation. The ruling body of a borough was commonly called its corporation, although the terms 'town council' and 'city council' were also used. Many boroughs had rights under their charters to hold certain types of court cases.

Around 1132, the Corporation of London was given the right to appoint two sheriffs to jointly serve the city and the county of Middlesex in which it was located, instead of the monarch appointing a Sheriff of Middlesex with jurisdiction over London as had previously been the case. Other boroughs later campaigned for the right to appoint their own sheriffs too, which would allow them to hold all types of court case. In 1373, Bristol was the next borough to be given the right to appoint its own sheriff. Bristol's elevation to being its own county was partly on the basis of its growing size and importance, and partly because the borough straddled the counties of Gloucestershire and Somerset (both of which held their courts some distance from Bristol) which had caused problems with the administration of the borough.

Other large boroughs later followed suit. The charters giving boroughs the rights to appoint their own sheriff generally did not use the term 'county corporate', instead using wording which made the borough into a new county and directed that the sheriff for that new county should be chosen by the borough corporation, rather than the monarch as was the case for other counties. One exception was the charter awarded to Coventry in 1451, which did explicitly use the term 'county corporate'. Although not a statutory term, 'county corporate' came to be used to describe these places which were legally counties, but where the right to appoint a sheriff rested with the borough corporation rather than with the monarch.

Some of the counties corporate were also the county town of the wider county in which they lay. In nine such cases (Carmarthen, Chester, Exeter, Gloucester, Lincoln, Newcastle upon Tyne, Norwich, Nottingham, and York) the area around the courthouse for the wider county was excluded from the county corporate, making such courthouses exclaves of the wider county. As well as larger towns and cities, some counties corporate were created to deal with specific local problems, such as border conflict (in the case of Berwick-upon-Tweed) and piracy (in the cases of Poole and Haverfordwest).